At the outbreak of WWII, Henry re-enlisted as a Private in 1939 however due to his injuries from WWI, he was not eligible for overseas service. With his extensive military experience, Henry trained at the University Armouries in Toronto before transferring to Newmarket #23 Training Centre where he was promoted to Company Sergeant Major (CSM). After the training camp closed in 1943, Henry was made Deputy Fire Marshall for all military camps in Ontario and stationed in Monteith, at a Prisoner of War Camp near Iroquois Falls, Ontario.